Its past, "have experienced" meaning they've already been through it
The correct answers would be "using contractions, slang terms, and colloquial expressions" and "using expressive punctuation". This way the writer brings the topic closer to the reader by making it "sound more like conversation". If you use "formal rules of grammar", it does not sound like a conversation, and "underlining words for emphasis" only draws your attention to those words. Mentioning your friend in the letter doesn't really affect anything.
The time you stop working could be a few different things.
Retirement
Off shift
Vacation
I’m not sure what your choices are.
John cage maybe. but you didn’t give possible answers sooo...
